In Shemot 24:3, regarding the term mishpatim, Rash"i citing Mechilta includes a list of items. Among them, he includes parah adumah (the laws of the red heifer.)
This is puzzling. The beginning of parshat Chukat refers to the laws of parah adumah as a chok, not a mishpat.
So, why is Mechilta including this among the mishpatim, here?
In Bamidbar Rabba 19,1 it describes that the Kohen that sprinkles the Mei Chattas (solution of red cow Ashes) on the Tamei whereby the _tamei becomes tahor and the sprinkler who was Tahor becomes Tamei is The "decree which is impossible to understand" as only G-d can bringing purity out of the ritually contaminated:
"זֹאת חֻקַּת" זש"ה (איוב יד, ד): "מי יתן טהור מטמא לא אחד" תמן תנינן: "העוסקין בפרה מתחלה ועד סוף מטמאין בגדים, היא גופה מטהרת בגדים". אמר הקדוש ברוך הוא: חקה חקקתי, גזירה גזרתי, אי אתה רשאי לעבור על גזרתי.
It seems that according to Rashi Bamidbar 19,2 the idea of purchasing and burning the Red cow and the laws that it shouldn't have a blemish not pulled a yolk is actually understandable.
The Cow has to be purchased with public funds as an atonement for the "son" i.e the golden calf which people donated their gold to make. The cow has to be red representing the sin which is red that we want to turn white i.e atone (this happen to the string on the Goat of Azazel on Yom Kippuras well). It has to be without blemish just like we had no blemish before we sinned with the golden calf. And it cannot have had a yoke on its back just like we took of the Yoke of Heaven from our backs:
"ויקחו אליך" - משלהם כשם שהם פרקו נזמי הזהב לעגל משלהם כך יביאו זו לכפרה משלהם
"פרה אדמה" - משל לבן שפחה שטינף פלטין של מלך אמרו תבא אמו ותקנח הצואה כך תבא פרה ותכפר על העגל
"אדמה" - על שם (ישעיהו א, יח) אם יאדימו כתולע שהחטא קרוי אדום
"תמימה" - על שם ישראל שהיו תמימים ונעשו בו בעלי מומין תבא זו ותכפר עליה' ויחזרו לתמותם
"לא עלה עליה עול" - כשם שפרקו מעליהם עול שמים
Since according to Seder Olam Rabba CHapter 6 straight after the 10 commandments Moshe went up for 120 days during that time the Golden calf had already been made, all the subsequent commandments including the Making of the Mishkan and Mizbeach mentioned at the end of Pasrshas Yisro and the rest of the Torah were given after the Golden calf was made. (Had they not sinned with the Golden calf they would have lived forever and not died like Adam before he Sinned.)
